Please try the below mentioned steps:
Right click on ther M Icon in the System Tray(Lower Right Corner)-->Click on Product Setup.
If you are a new user the windows that popups up will give you a form to register.Please complete it to register youself with McAfee. The information that you provide while registration would remain as your credentials to install McAfee from the website.
If are already registered , then on the window that popups you will find "Current user McAfee login" click on that and enter your User Name and password. This will succesfully verify your information.
Once this process is completed your product will get activated and you will start receiving updates.
This tutorial will help you to activate it online.